One recent development is of particular interest. James
Butterfield (168) has utilized the Prevost-Fechner-Benham Effect to
obtain colored images on ordinary black-and white television
receivers. The technique requires no modification in either
transmission or reception. In use, a proprietary Color Encoder is
attached to an ordinary black- and-white television camera lens. This
Encoder uses the basic Prevost-Fechner-Benham sequence code based on
Fig. 60. By referring to Fig. 60, one cycle of the Encoder may
be analyzed in six successive “frames” as was done
with Benham’s Top. Frames 1, 2, and 3 are blank (opaque). Frame
4 presents the “red primary image” to the viewer by interspersing
a cyan filter (the comple-mentary of red)* before the camera
lens. (It was noted earlier that the object to be colored with the
Prevost-Fechner-Benham should appear black on white surround.) Frame
5 presents the “green primary image” obtained through a
magenta filter (the complementary of green).* Frame 6 presents the
“blue primary image” obtained with a yellow filter (the
complementary of blue).* This complete sequence is then repeated at
the rate of 5 cps to be compatible with the domestic television
framing rate of 30 frames/sec.
Two points must be emphasized concerning Butterfield’s
technique. First, each of his “primary images” is a purely
black-and-white image, since the television camera is simply an
ordinary black-and-white camera. Second, the fact that the system
works to give color summation via the three Prevost-Fechner-Benham
“primaries” is apparently a new discovery. Composite hues
(flesh tones, chocolate pudding) are formed with surprising fidelity,
and they are actually more pleasing than the primaries, since the
composites have less flicker. The flicker present in the technique
is apparently its only serious drawback at present, but even this may be
useful in some applications, such as commercials. Finally, it should
be noted that Butterfield’s Color Encoder may be used in front
of a live TV camera, or with a motion picture camera (black-
and-white), or its effect may be dubbed by using an identical
sequence of colored illuminants upon the scene to be shot. The actual
filters used are proprietary information.
*
Thus effectively blocking the corresponding color in the image.
168. Butterfield, J. Electronic Color Television, Electronic Color
Company, Hollywood, Calif., 1965, p 1 |
